Lora Gateway Based on MicroPython ESP32

Lora has been very popular in recent years. The wireless communication module using this technology is usually cheap (using free spectrum), small in size, energy-efficient and has a long communication distance, and is mainly used for mutual communication between IoT terminals or data exchange with a host. There are many LoRa modules on the market, such as RFM96W, which is equipped with SX1278 (compatible) chip, which is very small. I use it with MakePython ESP32 as a gateway.

Next, I will use two LoRa nodes to send the temperature and humidity data to the gateway, and then upload it to the Internet through the gateway. Here you will learn how to upload remote data of multiple LoRa nodes to the cloud through the gateway.

• 1*MakePython ESP32

MakePython ESP32 is an ESP32 board with an integrated SSD1306 OLED display.

• 2*Maduino LoRa Radio

Maduino Lora Radio is an IoT (Internet of things) Solution based on the Atmel’s Atmega328P MCU and Lora module. It can be a real project for IoT projects(especially long-range, low power application )

• 2*DHT11

• 1*MakePython Lora

This is the schematic of Maduino Lora Radio.

Arduino Lora Radio module as LoRa node, we use it to send temperature and humidity data to the gateway.

(This WiKi introduces how to use Maduino Lora Radio and send and receive data)

The VCC and GND of DHT11 are connected to 3V3 and GND of Maduino, and the DATA pin is connected to D4 of Maduino.

Node 0 is in the park, node 1 is in the office building near the company, they are about 2 kilometers apart, and then I get their temperature and humidity data at home

Download TransmitterDHT11.ino, open it on Arduino IDE.

When adding a node, modify the node number accordingly. For example, now use 2 nodes, the first node to modify the nodenum = 0 to run the program, the second node to modify the nodenum = 1 to run the program, and so on, you can add more node.

int16_t packetnum = 0;  // packet counter, we increment per xmission
int16_t nodenum = 0;    //Modify the node number

Collect data and print it

String message ="#"+(String)nodenum+" Humidity:"+(String)humidity+"% Temperature:"+(String)temperature+"C"+" num:"+(String)packetnum;<br>Serial.println(message);
packetnum++;

Send a message to rf95_server

uint8_t radioPacket[message.length()+1];
message.toCharArray(radioPacket, message.length()+1);
radioPacket[message.length()+1]= '\0';     
rf95.send((uint8_t *)radioPacket, message.length()+1);

Open the serial monitor, you can see the collected temperature and humidity data, and send it out.

#0 Humidity:6.00% Temperature:27.00C num:0
Transmit: Sending to rf95_server
Sending...
Waiting for packet to complete...
Waiting for reply...
No reply, is there a listener around?

Put it aside, now we need to make the Lora Gateway.

This is the corresponding pin of the RFM96W module and MakePython ESP32. In order to facilitate connection with MakePython ESP32, I made a circuit board with the RFM96W module. Yes, there are two RFM96W on it, which can send and receive data at the same time, but now I only need one.

LoRaWAN is a low-power wide-area network based on LoRa, which can provide one: low power consumption, scalability, high quality of service, and safe long-distance wireless network.

Assemble MakePython Lora and ESP32 to make a gateway that can receive remote data and upload it to the Internet.

Download all ‘xxx.py’ files from WiKi and upload them to ESP32.

Open the LoRaDuplexCallback.py file, You need to make some adjustments so that your ESP32 can connect to the network and upload data to the server.

• Modify the API_KEY you obtained in ThingSpeak (I will introduce how to obtain it later)

#https://thingspeak.com/channels/1047479
API_KEY='UBHIRHVV9THUJVUI'

• Modify SSID and PSW to connect WiFi

ssid = "Makerfabs"
pswd = "20160704"

Find the on_receive (lora, payload) function in the LoRaDuplexCallback.py file, where you can tell ESP32 what to do after receiving the data. The following code parses and displays the received temperature and humidity data.

def on_receive(lora, payload):    
    lora.blink_led()   
    rssi = lora.packetRssi()        
    try:
        length=len(payload)-1   
        myStr=str((payload[4:length]),'utf-8')
        length1=myStr.find(':')
        myNum1=myStr[(length1+1):(length1+6)]
        myNum2=myStr[(length1+20):(length1+25)]  
        print("*** Received message ***\n{}".format(payload))
        if config_lora.IS_LORA_OLED: lora.show_packet(("{}".format(payload[4:length])), rssi)
        if wlan.isconnected():
            global msgCount
            print('Sending to network...')
            node = int(str(payload[5:6],'utf-8'))
	    if node == 0:
            	URL="https://api.thingspeak.com/update?api_key="+API_KEY+"&field1="+myNum1+"&field2="+myNum2
            	res=urequests.get(URL)     
		print(res.text)
	    elif node == 1:	
		URL="https://api.thingspeak.com/update?api_key="+API_KEY+"&field3="+myNum1+"&field4="+myNum2
		res=urequests.get(URL)
		print(res.text)

    except Exception as e:
        print(e)
    print("with RSSI {}\n".format(rssi))

Judging the number to distinguish the nodes, and uploading the data to the Internet through the URL, we can monitor the remote data of different nodes at any time. You can add more nodes and make similar changes to the code.

if node == 0:
	URL="https://api.thingspeak.com/update?api_key="+API_KEY+"&field1="+myNum1+"&field2="+myNum2
        res=urequests.get(URL)     
	print(res.text)

Steps:

1. Sign up an account in https://thingspeak.com/. If you already have one, sign in directly.
2. Click New Channel to create a new ThingSpeak channel.
3. Input name, Description, Select Field 1. Then save the channel on the bottom.
4. Click the API Keys option, copy the API Key, we will use it in the program.

You can see the data of node 0 and node 1 on the screen, although they are 2 kilometers apart.

Log in to your ThingSpeak account and click on the channel you created, you can see the uploaded temperature and humidity data.

The field1 graph and the field2 graphs are the humidity and temperature data of the Lora node 0, and the field3 graph and the field4 graph are the humidity and temperature data of the Lora node 1.